1. Field
The technological field relates to a secondary battery pack, and more specifically, to a secondary battery pack that includes a removable cell balancing system to be reused.
2. Description of the Related Technology
Generally, a secondary battery can be recharged and formed in a small size and large capacity. With the development of the lightweight and high functional portable radio devices, such as a mobile phone, a PDA, or a notebook computer, developments have been made on the use of a secondary battery as a driving power supply for portable radio devices.
In particular, the capacity of the secondary battery should be large to be used for an electric car, a hybrid car, or the like.
In order to make the capacity of the secondary battery large, a pack of a multi cell, not a single cell, is used, such that a high voltage can be applied to the secondary battery and the capacity of the secondary battery can be increased. However, the voltage of each multi cell tends to be unbalanced with the passage of time since the cell itself has charge and discharge characteristics.
The voltage difference between the cells in the secondary battery pack leads to unbalancing between the batteries, thereby resulting in the loss of the capacity of the secondary battery pack.
Therefore, various cell balancing systems and methods for balancing each cell have been developed so that all the cells of the secondary battery can be uniformly charged while preventing overcharging.
However, for cell balancing, to be performed, a cell balancing system should be attached to the secondary battery. In this case, the manufacturing cost of the secondary battery increases. Therefore, there is a problem in that the cost of the secondary battery is increased.